Response of pollution bio-monitors: <i>Pseudomonas</i> and <i>Bacillus</i> species to Local “Kpo-fire diesel” and industrial refined diesel in freshwater environment

Abstract

This paper reports the response of pollution bio-monitors such as Pseudomonas and Bacillus species to local and industrial diesel in freshwater environments of the Niger Delta, Nigeria. The illegal local refined diesel is popularly referred to as 'Bunkery diesel' or 'Kpo-fire diesel' in Niger Delta, Nigeria. It uses simply three major step/process; cooking or 'boiling' of crude oil, distillation and extraction at different temperatures into Petrol, Diesel and Kerosene but majorly Diesel and Kerosene are the final products. Standard ecotoxicological bioassay using pollution bio-monitors as indicator tools with different concentrations of local and industrial refined diesel were employed. Local and Industrial refined diesel concentrations of 0, 1.625, 3.25, 6.5, 12.5 and 25 mg/L were tested on Pseudomonas and Bacillus species at exposure intervals of 0, 4, 8, 12 and 24 hours for twenty four (24) separate set-ups. Percentage (%) log mortality (derived from log survival of the test organism) expressed as Median Lethal Concentration (LC₅₀ mg/L) was used as indices to monitor toxicity. The research shows that local and industrial refined diesel cause cell mortality. The 24 h LC₅₀ of the diesel were Bacillus +Local refined Diesel (20.54 mg/L) >Pseudomonas + Local refined Diesel (21.36 mg/L) >Bacillus +Industrial refined Diesel (21.88 mg/L) >Pseudomonas + Industrial refined Diesel (40.90 mg/L) (noting; the lesser the LC₅₀ the more toxic the toxicant). Comparatively, Local refined diesel is more toxic than Industrial refined diesel to all the test organisms. Also Bacillus sp. is more susceptible than Pseudomonas sp. to both local and industrial refined diesel. Based on these findings, the Local “illegal” diesel popularly called 'Bunkery diesel' or 'Kpo-fire diesel' refining should be discouraged in the Niger Delta of Nigeria especially in freshwater environment. As an industrial environment with high population which is prone to diesel spill impact, toxicity to Pseudomonas and Bacillus species could become a simple and fast bioassay for monitoring ecosystem response to these pollutants.

Keywords: Local refined diesel, 'Kpo-fire diesel”, “Bunkery diesel”, Ecotoxicity, Freshwater, Pseudomonas, Bacillus sp.